Samsung 205bw/Logic Board Issue?

[lcdman]

Hello All,

I looked though the other posts concerning this model but didn't see anything that had this logic board. So forgive me if I'm hijacking an old thread. I've just recapped the inverter/main board, the large one on its side is the only one that still is original. As it checked out alright. I used UCC KY & Panasonic FR caps. All but the small one and the large one were bulged/shot! But all I get now on the output is 13.34VDC. My guess is something is a miss on the logic board? If I understand correctly the logic board can cause start up issues even if the main board is putting out the correct voltage. Can anyone tell me where on the logic board to test? And what voltages should I see if its working correctly? Hopefully my uploaded pictures will help whomever chimes in to assist me.

Thanks As Always,
lcdman

[lcdman]

Re: Samsung 205bw/Logic Board Issue?

Hello,

Does anyone have any info on this logic board? I'd like to get a response so I know if I have to buy another one if it can't be repaired. If this is indeed the problem?

Take Care,
lcdman

[budm]

Re: Samsung 205bw/Logic Board Issue?

Is it the same power supply-inverter board as this one?
http://s807.photobucket.com/albums/y...msung%20205BW/
You are getting 13vdc output, then the power supply is working, the main board may not be sending out the signal to turn on the imverter cicruits.
Service manual:
http://elektrotanya.com/?q=showresul...oria=&kat2=all
Notes: there is no diagram in the service manual! But you can check the signals of the pins.

[lcdman]

Re: Samsung 205bw/Logic Board Issue?

Hello Budm,

Thanks for your reply. My inverter board is a little different. Must be a different
revision number. I looked through that service manual quickly. So I should be getting 3.3VDC and 1.8VDC on the voltage regulators on the logic board? Also I noticed that it said 14VDC on the inverter output? I'm uploading pics of my inverter board. There is some discoloration around the transformers. Could that be a factor on getting just the blue light on the power switch? How would I test those?

Thanks Again,
lcdman

[selldoor]

Re: Samsung 205bw/Logic Board Issue?

you will need to figure out which is the secondary winding - usually on this shape one contact is at one end and one the other.
No power to the board, meter on ohms2000, test until you get a high reading perhaps 800 to 1200 then test the same pins on the other transformers.

If the blue light stays on can you see a dark image on the screen
perhaps using a flashlight at an angle

Does the screen flash at all when you switch on

[lcdman]

Re: Samsung 205bw/Logic Board Issue?

Hello Budm,Selldoor,

The monitor was dead when it came to me to try to repair. And now I get 13.34VDC at the output connection and the blue power light comes on but nothing else. I attempted to test the transformers. Here are my results. Let me know if i'm even close to correct!

(T301) 2.638M ohms
2.637M ohms
1.080K ohms

(T302) 2.639M ohms
2.637M ohms
1.083K ohms

(T303) 2.642M ohms
2.638M ohms
1.084K ohms

(T304) 2.640M ohms
2.642M ohms
1.091K ohms

(T305) 2.634M ohms
2.637M ohms
1.125K ohms

(T306) 2.635M ohms
2.637M ohms
1.132K ohms

Thanks To All So Far,
lcdman

[budm]

Re: Samsung 205bw/Logic Board Issue?

(T305) 2.634M ohms
2.637M ohms
1.125K ohms

(T306) 2.635M ohms
2.637M ohms
1.132K ohms

These two look bad with over 1100 Ohms.

[lcdman]

Re: Samsung 205bw/Logic Board Issue?

Hello Budm,

So would those transformer values be a cause for the inverter not lighting up the ccfls? Where would be a good place to source replacements? Ebay? Any recommendations?

Thanks,
lcdman

[budm]

Re: Samsung 205bw/Logic Board Issue?

It will flash the lamps on then the circuit will go into shutdown because the lamps do not stay on. In the first 3 second when the inverter is commanded to turn on if it detect open connection of the lamp (any one of the lamp is not connected or or not stay on), or lamps draw too much current, the circuit will shutdown. I have some example of SAMSUNG 214t: http://s807.photobucket.com/albums/y...amsung%20214T/ the bad transformers are over 1000 Ohms.
I Google/Ebay 'SPI 8TR00051' and nothing come up for sale

[lcdman]

Re: Samsung 205bw/Logic Board Issue?

Hello Again Budm,

I didn't have any luck looking for a replacement transformer either. So am I understanding you correctly? You think the fault is those transformers or the ccfls? If its the inverter board and I or you can't find transformers, should I source another inverter board? Or return back to the owner.

Thanks For Your Assistance As Always,
lcdman

[budm]

Re: Samsung 205bw/Logic Board Issue?

The fault are those two transformers.

[ben7]

Re: Samsung 205bw/Logic Board Issue?

Repaired one of these before. Bad caps in PSU. Corrupt EEPROM on the logic board. It had exactly the same PCB's as yours.

Didn't have any problem with the backlights though.

[selldoor]

Re: Samsung 205bw/Logic Board Issue?

Does the back light flash on at all?